1. Field of the Invention
The present invention relates to a hook-bolt lock assembly for locking a door to a stationary frame element, in which a hook plate having its base-end portion pivoted to a casing has its front-end hook portion engaged with a socket member so that the door is locked to the stationary frame element.
2. Description of the Prior Art
In a conventional hook-bolt lock assembly, since only one hook-bolt plate is engaged with and disengaged from a socket member, the assembly is poor in mechanical strength. In addition, when the hook-bolt plate is swung from its engaging position toward its disengaging position, and vice versa, it is necessary for a user to insert a key into a rotor of a lock unit mounted on a front plate of a casing to have an operating arm rotated in a predetermined direction. However, such operation is cumbersome.